Scientia Iranica A (2020) 27(5), 2258{2263

Sharif University of TechnologyScientia Iranica

Transactions A: Civil Engineeringhttp://scientiairanica.sharif.edu

Suitability of brick kiln waste as a stabilizer for clayeysoils

A. Saanda, M.A. Zardaria;�, M.A. Keeriob, S.H. Shaikhc, and D.K. Bangwara

a. Department of Civil Engineering, Quaid-e-Awam University of Engineering, Science and Technology, Nawabshah, Sindh,Pakistan.

b. Department of Civil Engineering, Quaid-e-Awam University College of Engineering, Science and Technology, Larkano, Sindh,Pakistan.

c. Architecture and Engineering Services for Sindh Basic Education Program-II, Halcrow Pakistan, Pvt. Ltd, House No. C-172,Block C, Government Employees Cooperative Housing Society, Sukkur, Sindh, Pakistan.

Received 6 January 2018; received in revised form 28 June 2018; accepted 22 October 2018

KEYWORDSClayey soil;Brick kiln waste;Stabilizer;Bearing capacity;Dry density;Cohesion;Friction angle.

Abstract. Due to the growing use of brick masonry for the construction of buildings inPakistan, huge quantities of Brick Kiln Waste (BKW) are generated which can not onlycreate disposal problems but are hazardous to the environment. In order to resolve suchproblems, it is necessary to investigate the suitability of the BKW as a stabilizer for theclayey soils. For this purpose, an experimental program was carried out to stabilize clayeysoil with the BKW ranging from 5 to 40%. Basic geotechnical tests were performed onthe clayey soil blended with the BKW. The results showed that the clayey soil becamecoarser and more suitable as a subgrade material with the addition of the BKW. Therewas a negligible reduction in dry density up to 7% when the BKW added was 40%. Asexpected, the cohesion and friction angle of the blended soils decreased and increased,respectively, with the inclusion of the BKW. As compared to the clayey soil, the ultimatebearing capacity of the blended soil, characterized by 40% of the BKW, increased by 21%.This study showed that clayey soils stabilized with BKW could be used as a partial �llmaterial for highway embankments and foundations of buildings.© 2020 Sharif University of Technology. All rights reserved.

1. Introduction

Presently, �red bricks are widely used for constructingbuildings. Due to a constant increase in the populationof Pakistan, there is more demand for houses. Tomeet demand for houses, bricks are manufactured ona large scale. In Pakistan, approximately 18000 kilnsare in operation which �re about 45 billion bricks

*. Corresponding author. Tel.: 00923331225200E-mail addresses: abdullah.saand@gmail.com (A. Saand);muhammad.auchar@quest.edu.pk (M.A. Zardari);mantharali99@quest.edu.pk (M.A. Keerio);sabir.hussain@halcrowpk.com (S.H. Shaikh);daddan@quest.edu.pk (D.K. Bangwar)

doi: 10.24200/sci.2018.50198.1569

annually [1]. The fuel used for �ring bricks in kilnsconsists of wood and agricultural by-products such asrice husk, sugarcane bagasse, old pieces of clothes, etc.As a result, a huge quantity of waste consisting of ashand small pieces of bricks is generated on sites wherekilns are located. The Brick Kiln Waste (BKW) isnot disposed of properly, which is a current practicein Pakistan. The BKW gradually accumulates on thesites of the kilns. The accumulated BKW may createnot only disposal but environmental problems. Toalleviate these problems, it is necessary to investigatewhether the BKW can be used as a stabilizer for clayeysoils, which are considered as poor material for variouscivil engineering works.

Highway embankments and foundations of build-ings require massive quantities of �ll materials. The

A. Saand et al./Scientia Iranica, Transactions A: Civil Engineering 27 (2020) 2258{2263 2259

clayey soils may exhibit low bearing capacity, highcompressibility, and settlement. As a result, the pave-ments of roads may experience cracks and buildingsmay su�er from di�erential settlement, which mayreduce their service life. Under these conditions, theclayey soils may be stabilized with granular soils toachieve satisfactory performance. The use of the BKWas a partial �ll material with clayey soils in highwayembankments and foundations of buildings could be abetter option than disposal, which is costly.

Throughout the world, billions of tons of solidwaste are generated annually. E�orts are being madeto implement waste management practices to reducethe environmental problems of solid wastes [2{4].Nowadays, solid wastes are utilized in various civilengineering domains such as soil stabilization [5{8] andland�lls [9,10]. Fly ash has been utilized as a partial�ll material in highway embankments [11{14]. Ricehusk ash is also used as a partial construction materialin highways [15{17]. Waste ceramic dust [18], marbledust [19], and brick dust [20] have also been utilized forsoil stabilization. The authors are of the view that nostudy has been published on the suitability of BKW asa stabilizer for civil engineering construction projects.The purpose of this study is to assess the viability ofthe BKW as a partial �ll material for the constructionof highway embankments and foundations of buildings.For this purpose, index properties, compaction, shearstrength parameters, and ultimate bearing capacity ofthe clayey soil partially blended with the BKW aredetermined.

2. Materials and methods

2.1. MaterialsClayey soil samples were excavated from areas close toNawabshah city. The BKW was obtained from a localbrick kiln in the surrounding area of Nawabshah city(Figure 1). The BKW consists of ash of rice husk andwood and small pieces of broken bricks, which were�ner than Sieve 4. The larger pieces of the bricks werebroken and made �ner than Sieve 4. The BKW wasmixed with the clayey soil with an increment of 5% by

Figure 1. A view of brick kiln waste generated by a localbrick manufacturing work.

weight. This mixing process of the BKW with clayeysoil increased up to 40%.

2.2. Testing programThe particle-size distribution curves of the soils wereevaluated using ASTM D422 [21]. Liquid and plasticlimits were determined with ASTM D4318 [22]. Thesoils were classi�ed according to AASHTO classi�ca-tion system [23]. Moisture density relationship andshear strength parameters of the soils were evaluatedusing references ASTM D1557-12 [24] and ASTMD3080/D3080M-11 [25], respectively. Free swell ratioof the soils was determined using a procedure describedby Prakash and Sridharan [26].

3. Results and discussion

3.1. Liquid limit, plastic limit, and plasticityindex of the soils

Table 1 shows the values of plastic limit, liquid limit,and plasticity index of all soil samples. As expected,the values of the above-mentioned parameters of theblended soils decreased with an increase in content ofthe BKW. As compared to the clayey soil, the valuesof the liquid limit, plastic limit, and plasticity indexof the blended soil having 40% BKW were reducedby 27%, 28%, and 11%, respectively. The decreaseof consistency values of blended soils results from anincrease in coarse particles of the BKW.

3.2. Classi�cationThe particle-size distribution curves of the clayey soilmixtures blended with various proportions of the BKWare presented in Figure 2. It can be observed thatparticle sizes of clay and the BKW range from 2 mmto 0.01 mm and from 4.75 mm to 0.01 mm, respectively.For all mixes, the soils are well graded. The originalsoil is classi�ed as A-7-5 group (clayey soil), whichis considered as a poor soil. The blended soil wasimproved into A-4 (silty soil) and A-2-4 (silty or clayeygravel and sand) groups, when the BKW was increased

Figure 2. Particle size distribution curves of soils blendedwith 5 to 40% Brick Kiln Waste (BKW).

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Table 1. Index properties of the clayey soil blended with Brick Kiln Waste (BKW).

Serial no. Soil mixtureLiquidlimit(%)

Plasticlimit(%)

Plasticityindex(%)

passingfrom

#200 sieve (%)

AASHTOclassi�cation

1 Clay 47 35 12 73 A-7-52 Brick Kiln Waste (BKW) 21 19 2 26 A-2-43 Clay+5% BKW 45 34 11 68 A-7-54 Clay+10% BKW 44 33 11 64 A-55 Clay+15% BKW 42 33 9 57 A-56 Clay+20% BKW 40 30 10 49 A-57 Clay+25% BKW 39 29 10 40 A-48 Clay+30% BKW 38 29 9 36 A-49 Clay+35% BKW 37 28 9 34 A-2-410 Clay+40% BKW 34 25 9 32 A-2-4

from 10% to 30% and 35% to 40%. This implies thatthe blended soil became coarser with an increase inthe BKW than the clayey material. According toAASHTO classi�cation system, the A-7-5 and A-2-4groups represent the poor- and good-quality subgradesoils, respectively. A-2-4 soils are appropriate materialfor the construction of embankments. Soils belongingto A-4 group can also be used as a �ll material for low-height embankments in those locations where moistureis not expected to increase above the placement watercontent (see, e.g., [27]).

3.3. E�ect of BKW on moisture-densityrelationship of soils

Modi�ed Proctor compaction tests were carried out onsoil samples that contained clay, BKW, and blendedsoils. The Optimum Moisture Content (OMC) and themaximum dry density values of the blended soils wereevaluated (Figure 3). The values of OMC increased,and the dry density decreased with increase in theBKW (Table 2). This is because the BKW is aporous material, which absorbed more water, thus

Figure 3. Moisture density relationship of the soils mixedwith 5 to 40% Brik Kiln Waste (BKW).

increasing the OMC and reducing the dry density. Thevalues of dry density of the clay slightly reduced from18.5 kN/m3 to 17.9 kN/m3 and 17.2 kN/m3 when itblended with 5% and 40% of the BKW. The values ofthe dry density of the blended soils are comparable to

Table 2. Optimum moisture content and maximum dry density values of the soil mixed with di�erent proportions of theBrick Kiln Waste (BKW).

Serial no Soil mixture OMC(%)

Increase inOMC (%) as

compared to clay

Dry density(kN/m3)

Decrease in drydensity (%) as

compared to clay1 Clay 13 | 18.5 |2 Brick Kiln Waste (BKW) 20 | 16.4 |3 Clay+5% BKW 15 15 17.9 34 Clay+10% BKW 15 15 18 35 Clay+15% BKW 15 15 17.9 36 Clay+20% BKW 16 23 17.9 37 Clay+25% BKW 16 23 17.8 48 Clay+30% BKW 16.5 26 17.7 49 Clay+35% BKW 16.7 28 17.5 510 Clay+40% BKW 17.6 35 17.2 7

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those of a mixture of sand and gravel and well-gradedsands (see, e.g., [28]).

It is to be noted that maximum reduction in thevalue of dry density of the blended soil was 7% whenthe BKW added was 40%. This implies that if theBKW is available in large volumes, it can be utilizedby as high as 40% with clayey soil without a�ecting drydensity.

3.4. E�ect of BKW on shear strengthparameters of the soil

Shear strength parameters (cohesion and friction angle)of the clayey soil mixed with di�erent percentages ofthe BKW were determined through shear box tests.The cohesion of the blended soils decreased (Figure 4)and the friction angle increased (Figure 5) with anincrease in the BKW. The cohesion and friction anglevalues of the blended soils were decreased by 40% andincreased by 38%, respectively, when the BKW addedwas 40%. This is because the blended soils containedcoarse and angular particles of the BKW.

3.5. E�ect of the BKW on ultimate bearingcapacity of clayey soil

In order to �nd the potential of the clayey soilsstabilized with the BKW, the bearing capacity of an

Figure 4. E�ect of addition of brick kiln waste on thecohesion of clayey soil.

Figure 5. E�ect of brick kiln waste on the friction angleof clayey soil.

Figure 6. Ultimate bearing capacity of clayey soilblended with di�erent proportions of Brick Kiln Waste(BKW).

isolated square footing of 2 m � 2 m and depth of2 m was calculated through Terzaghi's bearing capacityequation (see, e.g. [29]):

qu = cNc+ DNq + 0:5 BN ; (1)

where qu, c, , D, and B are ultimate bearing capacity,cohesion, unit weight of the soil, depth of foundation,width of footing, respectively, and Nc, N , Nq areTerzaghi's bearing capacity factors.

The ultimate bearing capacity of the soils blendedwith the BKW is presented in Figure 6. The ultimatebearing capacity of the blended soils increased with anincrease in the BKW. The ultimate bearing capacityof the clayey soil mixed with 40% BKW increased by21%. The ultimate bearing capacity of the clayey soilblended with 25% of the BKW was about 430 kPa.According to International Code Council [30], theultimate bearing capacity of sandy gravel and/or gravelis about 430 kPa. This implies that the BKW canbe utilized with clayey soil as a foundation materialwithout compromise on bearing capacity.

3.6. E�ect of BKW on the swelling propertiesof the clayey soil

The free swell ratio of the blended soils decreased withan increase in the BKW (Figure 7). According to thecriteria suggested by Prakash and Sridharan [26], thedegree of expansion of clayey soil was moderate. Withthe addition of the BKW in the clayey soil up to 30%,the expansion of the blended soil became low. Finally,the degree of expansion of the blended soils becamenegligible when mixed with 35% to 40% of the BKW.

4. Conclusions

In this study, the suitability of the Brick Kiln Waste(BKW) as a stabilizer for clayey soils was examined.The main �ndings of this study are summarized below:

2262 A. Saand et al./Scientia Iranica, Transactions A: Civil Engineering 27 (2020) 2258{2263

Figure 7. Decrease in free swell ratio of the clayey soilblended with 5 to 40% Brick Kiln Waste (BKW).

1. With the addition of the BKW, the clayey soil be-came coarser and more appropriate as a partial �llmaterial for highways and foundations of buildings;

2. The dry density of the blended soil slightly reducedby 3% and 7% when the 20% and 40% values ofBKW were added, respectively;

3. Values of cohesion and friction angle of the clayeysoil were reduced and increased by 40% and 39%,respectively, when the BKW added was 40% invalue;

4. In comparison to clayey soil, the ultimate bearingcapacity of the blended soils increased by 21% whenthe BKW mixed was 40% in value;

5. The results presented in this study suggest that theBKW could be utilized as a stabilizer for clayeysoils to be used in highway embankments andfoundations of buildings.

Acknowledgements

The authors would like to thank Quaid-e-Awam Uni-versity of Engineering Science and Technology, Nawab-shah for providing access to Soil Mechanics Laboratoryfor conducting the tests reported in this study.

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Biographies

Abdullah Saand is a Professor at the Depart-ment of Civil Engineering, Quaid-e-Awam Universityof Engineering, Science, and Technology (QUEST),Nawabshah, Pakistan. He received PhD in StructuralEngineering from University of Technology Malaysia in2007. His research interests include polymer modi�edconcrete, properties of construction materials, andconcrete repair.

Muhammad Auchar Zardari received PhD fromLulea University of Technology, Lulea, Sweden inSoil Mechanics and Foundation Engineering in 2013.Presently, he is an Associate Professor at the De-partment of Civil Engineering, QUEST Nawabshah,Pakistan. His research interests include numericalmodeling of geotechnical structures, long-term stabil-ity of embankment dams, internal erosion of dams,geotechnical properties of waterlogged soils, and soilstabilization.

Manthar Ali Keerio is a Professor at the CivilEngineering Department at QUCEST Larkano. Hereceived PhD in Structural Engineering from QUESTNawabshah in 2017. His research interests include sup-plementary cementing materials and self-consolidatingconcrete.

Sabir Hussain Shaikh has obtained a Master ofCivil Engineering from QUEST Nawabshah in 2015.Presently he is working as Resident Engineer in Hal-crow Pakistan, Pvt. Ltd. His research interests are soilstabilization with solid waste materials.

Daddan Khan Bangwar is a Professor in CivilEngineering Department at QUEST Nawabshah. Hereceived PhD in Structural Engineering from QUESTNawabshah in 2016. His research interests include sup-plementary cementing materials and polymer modi�edconcrete.